Andrea Barontini

Andrea Barontini

I am a PhD student in physics but also an amateur pianist and an even more amateur futsal player

Publications

This is the list of my publications, including title and abstract. All the papers can be seen by clicking on the link.

The Path to N3LO Parton Distributions

Published in University of Milan, physics department, 2024

We extend the existing leading (LO), next-to-leading (NLO), and next-to-next-to-leading order (NNLO) NNPDF4.0 sets of parton distribution functions (PDFs) to approximate next-to-next-to-next-to-leading order (aN3LO). We construct an approximation to the N3LO splitting functions that includes all available partial information from both fixed-order computations and from small and large x resummation, and estimate the uncertainty on this approximation by varying the set of basis functions used to construct the approximation. We include known N3LO corrections to deep-inelastic scattering structure functions and extend the FONLL general-mass scheme to O(αs^3) accuracy. We determine a set of aN3LO PDFs by accounting both for the uncertainty on splitting functions due to the incomplete knowledge of N3LO terms, and to the uncertainty related to missing higher corrections (MHOU), estimated by scale variation, through a theory covariance matrix formalism. We assess the perturbative stability of the resulting PDFs, we study the impact of MHOUs on them, and we compare our results to the aN3LO PDFs from the MSHT group. We examine the phenomenological impact of aN3LO corrections on parton luminosities at the LHC, and give a first assessment of the impact of aN3LO PDFs on the Higgs and Drell-Yan total production cross-sections. We find that the aN3LO NNPDF4.0 PDFs are consistent within uncertainties with their NNLO counterparts, that they improve the description of the global dataset and the perturbative convergence of Higgs and Drell-Yan cross-sections, and that MHOUs on PDFs decrease substantially with the increase of perturbative order. Read more

Determination of the theory uncertainties from missing higher orders on NNLO parton distributions with percent accuracy

Published in University of Milan, physics department, 2024

We include uncertainties due to missing higher order corrections to QCD computations (MHOU) used in the determination of parton distributions (PDFs) in the recent NNPDF4.0 set of PDFs. We use our previously published methodology, based on the treatment of MHOUs and their full correlations through a theory covariance matrix determined by scale variation, now fully incorporated in the new NNPDF theory pipeline. We assess the impact of the inclusion of MHOUs on the NNPDF4.0 central values and uncertainties, and specifically show that they lead to improved consistency of the PDF determination with an ensuing moderate reduction of PDF uncertainties at NNLO. Read more

Photons in the proton: implications for the LHC

Published in University of Milan, physics department, 2024

We construct a set of parton distribution functions (PDFs), based on the recent NNPDF4.0 PDF set, that also include a photon PDF. The photon PDF is constructed using the LuxQED formalism, while QED evolution accounting for O(alpha), O(alpha alphas) and O(alpha^2) corrections is implemented and benchmarked by means of the EKO code. We investigate the impact of QED effects on NNPDF4.0, and compare our results both to our previous NNPDF3.1QED PDF set and to other recent PDF sets that include the photon. We assess the impact of photon-initiated processes and electroweak corrections on a variety of representative LHC processes, and find that they can reach the 5% level in vector boson pair production at large invariant mass. Read more

Pineline: Industrialization of High-Energy Theory Predictions

Published in University of Milan, physics department, 2023

We present a collection of tools automating the efficient computation of large sets of theory predictions for high-energy physics. Calculating predictions for different processes often require dedicated programs. These programs, however, accept inputs and produce outputs that are usually very different from each other. The industrialization of theory predictions is achieved by a framework which harmonizes inputs (runcard, parameter settings), standardizes outputs (in the form of grids), produces reusable intermediate objects, and carefully tracks all meta data required to reproduce the computation. Parameter searches and fitting of non-perturbative objects are exemplary use cases that require a full or partial re-computation of theory predictions and will thus benefit of such a toolset. As an example application we present a study of the impact of replacing NNLO QCD K-factors in a PDF fit with the exact NNLO predictions. Read more

Master thesis

Published in University of Rome La Sapienza, physics department, 2021

Precision physics is nowadays considered to be the key to understand many unknown aspects of the phenomenology beyond the Standard Model (SM) and, in the next future, with the coming, for instance, of the LHC (Large Hadron Collider) phase III, the experimental precision will considerably increase. This requires the theoretical precision to improve as well, at least at the same level, in order to make the distinction between Standard Model and new physic signals possible. This thesis arises in this framework and, in particular, in the context of precision predictions on hadron collider processes. The most relevant contribution to such processes is given by QCD but, in some kinematical regimes, it can not be treated in a standard perturbative way because of the appearance of non-perturbative mass logarithmic terms. In these cases, in order to obtain accurate phenomenological predictions, it is necessary to resum such terms to all orders. The main goal of this thesis is then the construction of a method to include mass-power corrections to the results obtained trough the resummation, in such a way to obtain a prediction that is reliable in a wide kinematic region. This method is completely general but, for clarity sake, it is applied to deep-inelastic scattering and, in particular, to the proton electromagnetic structure functions. The final predictions for such observables are obtained with different prescriptions, some of which constitute the original proposal of this thesis, and their consequences are analyzed in detail. Moreover, the proposal of this thesis will soon make possible to treat the N3LO deep-inelastic scattering and so it will give access to the next generation of the parton distribution functions (PDFs). Read more

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